Methods and compositions for improving the adhesion of resins to hard tissue, i.e., dentin or enamel, is an ongoing goal in the dental arts. Improved adhesion leads to longer lasting restorations and reduced tooth sensitivity. Numerous methods for preparing teeth for the application of a dental restorative material (such as a sealant, filling material, cementation of indirect dental restorations or the like) have accordingly been developed, including acid etch and priming steps.
Acid etchants are commonly used to remove a smear layer and demineralize the tooth surfaces so as to promote effective mechanical bonding of the restorative material. However, the use of an etchant has a disadvantage in that it must be washed off after application, requiring the time-consuming procedure of application, washing, and drying. A further disadvantage of etchants is the perception that use of strong etchants can increase dental sensitivity in some patients.
In addition to acid etch procedures, adhesive strength is also improved by use of a primer. Primers are generally surface-active compounds that exhibit both an affinity for dentin and adhesive resin systems and participate in the polymerization process, thereby promoting adhesion between the primarily hydrophilic dentin and the predominantly hydrophobic polymeric adhesives or monomers from which they are formed. Primers are applied to dentin in solution form, commonly used solvents including acetone, ethanol, water, and various mixed solvent systems. While effective for promoting bonding, primers however are often applied using an additional step.
Current resin cement materials used for the cementation of dental restorations made from metal alloy, ceramic/porcelain, or composite material require a separate bonding procedure to ensure sufficient and effective bonding of the dental restoration to the tooth. Often a separate procedure including etching and applying a bonding adhesive to the tooth or restoration is required, rendering the cementation procedure time consuming and more complex.
Conventional luting cements such as glass ionomer cement, zinc phosphate cement, and polycarboxylate cement are typically used for cementing metal restorations without a separate bonding step. However, the luting cements are not suitable for cementing composite or ceramic restorations. Additionally, the bonding ability of the luting cements to tooth structure is poor.
There accordingly remains a need in the art for improved dental cement materials providing improved adhesion to a tooth surface and a dental substrate, and yet which can be applied in a fewer number of steps.